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Abstract:: This experiment was conducted to evaluate the effects of feeding a Bacillus-based direct-fed microbial (DFM) on performance, nutrient digestibility, rumen fermentation, and metabolic response of lactating dairy cows. Sixty-eight lactating (50 ± 6 d in milk) Holstein-Friesian (n = 20) and Swedish Red (n = 48) cows were enrolled to a 15-wk experiment. Cows were blocked by breed, lactation number, and days in milk and, within blocks, assigned to 1 of the 2 treatments: (1) basal partial mixed ration (PMR) without DFM (n = 34; CON) or (2) basal PMR with the addition of 3 g/head per day of a DFM containing Bacillus licheniformis and Bacillus subtilis (n = 34; DFM). The DFM was mixed in a protein pellet, whereas the CON group was fed the same pellet without DFM (1 kg/cow per day). The PMR contained 53% clover grass silage and 47% compound feed plus 3 kg of a concentrate (dry matter basis) offered during milking. Milk yield and production efficiency were recorded daily, whereas milk samples were collected for 24 h every second week of the study for milk composition. During the experimental period, fecal, rumen fluid, and blood samples were collected from each cow for apparent nutrient digestibility, rumen fermentation, and metabolic responses, respectively. All data were analyzed using the MIXED procedure of SAS. No treatment effects were observed on cows final body weight and daily dry matter intake. However, cows fed DFM had a greater milk yield, milk production efficiency, lactose and total solids yield, and also tended to have a greater energy-corrected milk production efficiency and milk protein yield. No significant differences were observed on nutrient digestibility and total volatile fatty acids, but molar proportion of acetate was greater for cows fed DFM. In contrast, molar proportion of propionate was greater and butyrate tended to be greater for CON. Cows fed DFM had greater mean plasma insulin-like growth factor-I (IGF-I), but no differences were observed for plasma glucose and insulin. In summary, supplementing a Bacillus-based DFM benefited productive responses of lactating dairy cows, while also modulating rumen fermentation and serum IGF-I.

Two experiments were designed to evaluate the effects of altering body condition score (BCS) and the profile of a fatty acid (FA) supplement on the metabolism of Bos indicus Nellore females. In experiment 1, 16 and 24 B. indicus heifers and nonlactating cows, respectively, were assigned to (1) maintenance diet (MNT-MNT; n = 10), (2) maintenance diet and BCS loss (MNT-LSS; n = 10), (3) maintenance diet supplemented with calcium salts of soybean oil for 30 d and BCS loss for 40 d (MNT+CFA-LSS; n = 10), and (4) maintenance diet for 30 d and BCS loss for 40 d with a diet containing calcium salts of soybean oil (MNT-LSS+CFA; n = 10). Following the BCS loss period, MNT-LSS, MNT+CFA-LSS, and MNT-LSS+CFA were fed a diet to promote the gain of BCS. In experiment 2, 40 Bos indicus nulliparous heifers were assigned to (1) maintenance diet (MNT-MNT; n = 10), (2) BCS loss followed by a BCS gain (LSS-REM; n = 10), (3) BCS loss followed by a BCS gain diet with CFA of palm oil (LSS-REM+PLM; n = 10), and (4) BCS loss followed by a BCS gain diet with CFA of soybean oil (LSS-REM+SOY; n = 10). Blood samples were obtained for serum haptoglobin and fecal samples for pH (experiment 2 only). In experiment 1, a treatment × day interaction was observed for BCS during the 60-d BCS loss and gain period. Animals assigned to MNT-MNT had a greater BCS than the other treatment groups on d 40 and 60 of the experiment, but no other differences were observed. Moreover, a treatment × day interaction was observed for serum haptoglobin, as on d 60, MNT-LSS had a greater mean serum haptoglobin concentration. In experiment 2, a treatment × day interaction was also observed for BCS. From d −4 to 0, LSS-REM and LSS-REM+SOY had a reduced BCS versus MNT-MNT, but also lower for LSS-REM versus MNT-MNT on d 1, and LSS-REM+PLM versus MNT-MNT on d −1 and 0. For serum haptoglobin, no treatment or treatment × day interaction was observed. A treatment × day interaction was observed for fecal pH. From d −10 to 0, MNT often had a lower fecal pH, but during realimentation, LSS-REM heifers had a reduced fecal pH on d 1, 4, and 10. In summary, we failed to demonstrate an increase in serum haptoglobin due to a BCS loss. Still, supplementation with calcium salts of FA alleviated the increase in haptoglobin and maintained fecal pH at more stable values during realimentation, regardless of the FA profile of the supplement.

Optimization and support of health and performance of preweaning dairy calves is paramount to any dairy operation, and natural solutions, such as probiotics, may help to achieve such a goal. Two experiments were designed to evaluate the effects of direct-fed microbial (DFM) Enterococcus faecium 669 on performance of preweaning dairy calves. In experiment 1, twenty 4-d-old Holstein calves [initial body weight (BW) 41 ± 2.1 kg] were randomly assigned to either (1) no probiotic supplementation (CON; n = 10) or (2) supplementation with probiotic strain E. faecium 669 during the preweaning period (DFM; n = 10) at 2.0 × 1010 cfu/kg of whole milk. Full individual BW was analyzed every 20 d for average daily gain (ADG) and feed efficiency (FE) determination. In experiment 2, thirty 4-d-old Holstein calves (initial BW 40 ± 1.9 kg) were assigned to the same treatments as in experiment 1 (CON and DFM). The DFM supplementation period was divided into period I (from d 0 to 21) and II (from d 22 to 63), with weaning occurring when animals were 67 d of age. During the entire experimental period, DFM was mixed into the whole milk at a rate of 1.5 × 1010 and 2.5 × 109 cfu/kg of whole milk/calf per day for periods I and II, respectively (6-time reduction). Full individual BW was taken every 21 d. As a routine of the experiment, calves were monitored daily, and diarrhea cases were evaluated using a daily 3-point fecal score. For both experiments, all data were analyzed using calf as the experimental unit. In experiment 1, DFM-supplemented calves were heavier on d 40 (+ 4.5 kg) and 60 (+ 6.5 kg) and had a greater ADG (+ 118 g) versus CON. In experiment 2, supplementation with DFM significantly tended to reduce diarrhea occurrence. Treatment × day and treatment × week interactions were observed for BW, ADG, and gain-to-feed ratio. Dairy calves supplemented with DFM were 1.8 and 3.5 kg heavier on d 42 and at weaning, respectively, and had a greater ADG from d 21 to 42 (+ 52 g) and 42 to 63 (+ 77 g) and gain-to-feed ratio from d 42 to 63 (+ 8.6%). In summary, supplementation of E. faecium 669 to dairy calves improved preweaning performance, even when the dose of the DFM was reduced by 6- to 8-times. Additionally, initial promising results were observed on diarrhea occurrence, but further studies are warranted.

This experiment was conducted to evaluate the effects of feeding a Bacillus -based direct-fed microbial (DFM) on performance, nutrient digestibility, rumen fermentation, and metabolic response of lactating dairy cows. Sixty-eight lactating (50 ± 6 d in milk) Holstein-Friesian (n = 20) and Swedish Red (n = 48) cows were enrolled to a 15-wk experiment. Cows were blocked by breed, lactation number, and days in milk and, within blocks, assigned to 1 of the 2 treatments: (1) basal partial mixed ration (PMR) without DFM (n = 34; CON) or (2) basal PMR with the addition of 3 g/head per day of a DFM containing Bacillus licheniformis and Bacillus subtilis (n = 34; DFM). The DFM was mixed in a protein pellet, whereas the CON group was fed the same pellet without DFM (1 kg/cow per day). The PMR contained 53% clover grass silage and 47% compound feed plus 3 kg of a concentrate (dry matter basis) offered during milking. Milk yield and production efficiency were recorded daily, whereas milk samples were collected for 24 h every second week of the study for milk composition. During the experimental period, fecal, rumen fluid, and blood samples were collected from each cow for apparent nutrient digestibility, rumen fermentation, and metabolic responses, respectively. All data were analyzed using the MIXED procedure of SAS. No treatment effects were observed on cows final body weight and daily dry matter intake. However, cows fed DFM had a greater milk yield, milk production efficiency, lactose and total solids yield, and also tended to have a greater energy-corrected milk production efficiency and milk protein yield. No significant differences were observed on nutrient digestibility and total volatile fatty acids, but molar proportion of acetate was greater for cows fed DFM. In contrast, molar proportion of propionate was greater and butyrate tended to be greater for CON. Cows fed DFM had greater mean plasma insulin-like growth factor-I (IGF-I), but no differences were observed for plasma glucose and insulin. In summary, supplementing a Bacillus -based DFM benefited productive responses of lactating dairy cows, while also modulating rumen fermentation and serum IGF-I., (© 2023.)